Flash and Supergirl: Interdimensional Couple
by cornholio4
Summary: The Fastest Man Alive of one Earth and the Girl of Steel from another are the multiverse's first ever interdimensional couple, see how that plays out especially with their friends meet. Barry/Kara.
1. Chapter 1

**Sorry I am not so good at being able to continue my stories when I am on a writer's block for that story, but seeing as I wanted to write something that can get noticed and I have seen how popular the crossover stories between the Flash and Supergirl are, I wanted to see if I can write a crossover (unfortunately the actual TV crossover has not aired here in the UK yet). I have watched some more episodes of the Supergirl show (still planning on watching them more frequently when the season comes out on DVD) and I have watched a lot of the Flash with my Season One DVD (didn't think I would be that excited when I heard the spinoff show was announced since I was a big fan of Arrow but I now think this Flash Show is better than Arrow though I still like that show). I was also mostly inspired by the story A Girlfriend From Another Universe by MarvelDC31. I also think this is my first time writing a story pairing Kara up with anyone who wasn't Spider-Man.**

It was some time since Barry Allen had learned of the parallel worlds that existed and how to travel between them, it was safe to say that Zoom was gone so he was exploring some of the other worlds helping out when he could. He found this earth where he met a superhero called Kara or Supergirl as she went by and well he now had an alien girlfriend from another Earth. Because of having found his new girlfriend here this was his favourite Earth to visit though he did visit Harry from time to time on Earth 2, he saw another Earth where he was the Flash but looked like his dad there (the Trickster there looked just like the old photos of James Jesse from his old reign of terror that he saw when the 2nd Trickster came to town in his Central City) and another where he was the Flash but looked like Kevin from We Need to Talk About Kevin.

Right now he was in her universe, in a karaoke place (not unlike the one he once went too with Caitlin) on stage singing along to _I Want You Back_. Right now a friendly face he had met there James Olsen was eating along with his girlfriend Lucy Lane and her father, Samuel Lane who was a general in the United States Army. "Barry can sing, can't he?" James asked Lucy who nodded them both knowing about Barry coming from another Earth but General Lane didn't.

"Well your friend is lucky he never has to have the worries that Metropolis and National City faces with the alien cousins in them, I bet he leads a peaceful live in Central City." General Lane told them and they tried hard not to laugh of General Lane not knowing how wrong he was. "Yes not need to worry about Supergirl or that other guy that shows up sometimes since some time ago, the Flash or something. Probably forming a group of super friends or something..." General Lane muttered and James glared at him, he and the General did not get along too well with General thinking he was not good enough for Lucy and because he did not like that he was the famous best pal of Superman.

After Barry was done James and Lucy were amongst those clapping when Barry was done and they were packing up, "Let's see if you ever appear on the TV son." General Lane told him as he left. As they were leaving James told Barry of how paranoid he was against the aliens on Earth.

"Sounds just like a General on my Earth, General Eiling... seems like he was just as much as a jerk but Eiling mellowed out after I saved him from a telepathic gorilla." Barry told them causing them to look astonished but laughed. "Hey I have already told Kara of some of my rogues' gallery the Reverse Flash, the Trickster, Captain Cold..." Barry told them and they could not help but laugh at Captain Cold's name.

Kara came and gave Barry a hug and kiss on the lips before they faced the other happy couple, "Do you guys want to come over and join us because we are going to spend the afternoon at my place watching Netflix." Kara asked and they nodded.

"That's good; I am looking forward to see if your Earth's Netflix has Daredevil, Netflix or the Unbreakable Kimmy Schmidt." Barry told them and from the looks of their faces it looked like the shows existed here. "Awesome that means if you have Daredevil and Jessica Jones here then you also have the Avengers here as well." Barry told them as the couples parted from each other and Barry telling Kara he was going back to his Earth for a while but he would be back later.

Later in the day James and Lucy were on the couch in Kara's apartment along with Winn Schott as Kara was having the Netflix set up. Then there was a knock on the door and Kara answered the door, "Hey Barry." Kara greeted Barry at the door opening it to see him there.

"Sorry Kara I hope you didn't mind but I brought two of my best friends along with me." Barry told her and she did not look like she minded. Barry then went in with a guy and girl. "Kara these are my friends who help me out as the Flash, Cisco Ramon and Caitlin Snow." Barry said then facing his two friends. "guys this is my new girlfriend Kara Danvers and her friends Winn Scott, James Olsen and Lucy Lane." Barry told them as they sat down.

"Surprises me that this place looks more like our Earth than Earth 2 did, kind of expecting another evil me but with a goatee." Cisco said looking around while Caitlin told them that Cisco was kind of their geek.

"So you have Star Trek as well, do you have aliens as well?" Winn asked with Cisco and Caitlin eyes widening.

"Well we have dealt with metahumans, beings from another worlds but in the Borg, Darth Vader or Xenomorph sense we have not seen any aliens." Cisco told them and Caitlin groaned at more of his references.

"Well it's nice to meet you so if you want to sit down we can start watching Netflix." Kara told them as they sat down and Kara put on a movie for them to watch. Barry then used his super speed and a second later he was sitting next to Kara with his arm around her neck with them both smiling at each other.

"Do you have any superheroes on this Earth?" Caitlin asked with everyone then turning to Kara and Cisco and Caitlin both realised the implication. "Typical it would be another hero that Barry managed to end up with. So do you shoot heat rays from your eyes, are you super strong, super fast or can you fly?" Caitlin asked.

"All of the above." Kara told them and their jaws dropped, "Yeah I am known as Supergirl, the only main hero that everybody knows about is my cousin Superman who is in Metropolis and we both uses our powers for good." Kara told them.

"Well that's cool but what is your origin, most of our Metahumans go their powers from a particle accelerator exploding." Cisco told them and Barry wondered how they would react to this.

"Well me and my cousin are from a different planet and we both got our powers from the rays of Earth's yellow sun." Kara told them and their jaws if possible dropped even further.

" **WHAT?** "

 **Here Zoom has been defeated, Lucy and James are still together and Barry and Kara are together themselves.**

 **Have to admit General Lane annoys me (a part of me almost wishes he would become a straight villain only because of knowledge of his behaviour in the New 52 universe and his actions during the comics New Krypton storyline, funnily enough Lucy somehow gets a pass from me despite her actions in that story) but somehow I cannot fully hate him, part of it is maybe because for some reason I really like his voice (I think it also has to do with an episode of Superman the Animated Series called Monkey Fun where he had a role in a flashback and near the ending of the episode which showed him to be a nice guy and good parent from what little we saw of him in that episode). Yeah I had to make that comparison between Lane and Eiling since it is even noticed under expy on the Supergirl TV tropes page and I even put in on the WMG page on the Supergirl show that Barry would mention Eiling if he met General Lane.**

 **Also can you see if you can spot the references I managed to snuck in (not all of them are just about the Supergirl and Flash shows), some of them I could not resist putting in.**


	2. Chapter 2

It was about 20 minutes into the first episode of the Unbreakable Kimmy Schmidt when Cisco and Caitlin found their voices again. "So you are the friendly 'I come in peace' type of alien?" Cisco asked looking like he was not actually done freaking out yet, Barry looked quite annoyed thinking Cisco was going to be asking her a bunch of alien based questions but Kara did not look too bothered herself.

"Yes, I came from a planet called Krypton which exploded when I was in my early teens, me and my baby cousin Kal El were both sent to Earth but my pod got knocked off course and by the time I had landed he was already an adult and being a superhero himself." Kara told them and Cisco and Caitlin looked like they were cool for now as they went back to watching the show. "Yes, it is just me, Kal and someone called the Martian Manhunter who are heroes who protect the public." Kara told them and Cisco then looked at her realising something by her words.

"Wait so you only have three superheroes on this world?" Cisco complained and those native to the Earth just shrugged. Cisco looked like he was upset and whined "so you guys have no Flash, no Atom, no Firestorm or not Green Arrow?" Cisco then looked like he was pouting and Kara then got a scrapbook and told him that if it made him feel better he could read that.

Cisco then curiously looked at it and saw it was a scrapbook of various newspaper articles of events involving both Superman and Supergirl and he looked through it excitedly. Cisco then found the article of Supergirl fighting Vartox with his Axe and showed everyone it. "I don't like to brag but I am the goo too people to naming villains on our Earth so I have the perfect name for this guy, the Lumberjack." Cisco said pointing to Vartox's axe in the picture which caused Caitlin to groan but everyone else just laughed.

"So Barry, I think you mentioned something about being a cop?" Winn asked which caught the interest Lucy and James but Barry laughed at this.

"I work for Central City's Police force yes but I work in the crime lab, my job is basically to examine the scene of the crime after anything exciting happens so I don't know if that qualifies me to be a cop." Barry told them which caused James and Lucy to look a little disappointed. "Yeah, one of the detectives also basically just about raised me and her daughter has basically been my best friend since before then." Barry told them.

"Well what happened to your parents?" Lucy asked with Cisco and Caitlin frowning knowing that Barry will hate to answer that and in their minds it reminded them so much of a man that they had respect for so long only to turn out to be an evil human being whose only concern while working for them was making sure that he got home.

Barry paused for a second before deciding to get it over and done with so he would not have to tell the story again anytime soon. "My mother died when I was young and my father went to prison for her murder..." Barry muttered to the shock of the residents of the Earth. Noteworthy for Cisco and Caitlin was that Barry must not have told Kara this story yet as she seemed just as shocked as the rest of them.

Winn then decided to pat Barry on the back while interrupting him saying "my dad is in prison too, feel for ya bro." Winn told him with a smile "so I guess us people with scumbags for fathers have to stick together, my dad was a real bad man so I guess yours was one was well. I mean wonder what went through his mind during whatever dispute they must have been having..." At this Cisco and Caitlin groaned with their hands covering their faces.

Barry then glared angrily at Winn smacking his hand away and then used his super speed to run away with Cisco and Caitlin glaring at Winn. "Barry's father was FRAMED for his mother's murder by an evil supervillain; it was the most traumatic experience of his life." Caitlin clarified to Winn with him realising what he had just done with his words and looked extremely apologetic.

"I will go and talk to him." Kara told them taking of her glasses as something told her that she would need to change before speaking to him...

**F&S:IC**

Barry had decided to get some air so during his run at super speed he changed into his Flash suit and had now ran across National City helping several people across the street before deciding to sit on a hill outside National City's entrance sitting down whistling to himself. "You okay?" asked a voice and Barry turned his neck around and looked up to see to see Kara floating in the in her Supergirl suit. Kara then floated back down so that she was now sitting next to Barry.

"Yeah just fine, I didn't mean to snap at Winn like that, it's just..." Barry said looking like he was holding back tears and Kara held him in a hug letting him cry on her shoulders. Barry then let the tears out and after she let go he then gave her a thankful look.

"I remember that night so well, I was eleven years old and it started out as a normal night until I saw yellow light and a man in the yellow light. Next thing I knew I was outside and by the time I got home there was police, my mum dead and my father was arrested for her murder..." Barry muttered with Kara putting him back in her hands to comfort him if she needed to.

"I spent most of my life chasing after the impossible, trying to prove my father innocent and find out what happened. It was only after I had become the Flash that I would be able to find out with the details coming from the man himself who had done it – the Reverse Flash." Barry told Kara getting angry at having to think about Eobard Thawne again. "Eobard Thawne was a man from the future who tried to become me, getting powers the same way I got him and when he couldn't be me he became my arch enemy. He went back in time to kill me, he fought my future self and my future me got me to saftey. Thawne decided if he couldn't kill me he would kill my mum but it got him stuck in the past, after I dealt with him I managed to get my father released." Barry said with Kara hugging him even further and he turned the hug growing a smile.

"I remember coming to terms with the fact that my home planet was destroyed and my baby cousin who I was supposed to help didn't need my help..." Kara said pausing but then her eyes widened. "Wait a minute, the future... time travel?" Kara asked perplexed and Barry laughed at this.

"Yes I am so fast I can travel to other dimensions and travel through time, I will have to give you more details about that some other time." Barry told her with a laugh as they then shared a kiss. They then realised some people nearby were taking pictures on their cell phones and Kara groaned realising that the story of Supergirl and the Flash caught kissing would be a headline for CatCo the next day.

 **Yeah in the publicity of the first episode of Supergirl, they said that the opponent would be an extremely obscure and minor Wonder Woman villain called the Lumberjack, so they gave him the axe of a minor character and the name of a different alien character (Vartox in the comics if you don't know is actually an alien superhero friend of Superman who apparently been protecting his planet since Superman was a tot, I think he had a crossover with Power Girl rather recently though I am not a fan of Power Girl myself).**

 **Since as one reviewer pointed out, why General Lane came to the karaoke place? I am sorry I did not make it clear but Lucy pretty much made him come still thinking he can get along with James.**


	3. Chapter 3

After that everyone had went home, Kara and the others said goodbye to Barry, Caitlin and Cisco before Barry took them back to their own worlds. As Kara predicted the kiss between Supergirl and the Flash was what everyone was talking about. "So this Flash keeps coming out of nowhere, not even helping full time here and it seems he already has the heart of Supergirl, if only I could get an interview..." Kara's boss Cat Grant had told her in her office the next day and Kara didn't think that it would be possible for her to get an interview from Barry.

Kara went home and using her x ray vision she saw that Barry was in her apartment waiting for her, "Today was slow in Central City so I thought I would surprise you but coming here." Barry told Kara as they embraced eachother in a hug. "So I guess you had to deal with the story of the kiss those people caught us doing?" Barry asked and Kara shrugged her shoulders with a motion that said 'what can you do?' "Well Cisco and Caitlin told me they would not mind coming here again and there are two people who are practically my family Joe and Iris who wants to come and meet you. Also Oliver my fellow hero who calls himself..." Barry told her and they then heard the door knocking and Kara knew right away who it was when she answered the door.

It was Eliza Danvers who came in holding a newspaper and Kara hugged her and then faced Barry, "Barry this is my foster mum Eliza Danvers." Kara told Barry and she then faced Eliza again. "Mum, this is my boyfriend Barry Allen." Kara told her as Eliza then shook Barry's hand.

"So you must be the one they are calling the Flash." Eliza told Barry holding up the newspaper to show the kiss between Supergirl and the Flash on the front page. Kara and Barry then gave weak smiles and Kara knew from Eliza's face and posture she wanted to know about her new superhero boyfriend.

"Well nice to meet you Mrs Danvers, I am Barry Allen... I work in a crime lab... I had gotten speed powers from an accident... and I am from the Earth of another universe..." Barry said deciding he should get it all out of the way meeting his girlfriend's mum.

Eliza then looked shocker over Barry's story and Kara gave him a face as well, "Well my daughter is an alien so I guess I can beleive your story." Eliza then told Barry putting him into a hug and Kara was gave since it meant that Barry also had Eliza's approval.

"When I saw the picture of Kara kissing you, I was afraid you might have been the result of some experiment by the DEO..." Eliza told him and he gave her a confused look. "The Department of Extranormal Operations, they are a secret government group that investigates alien presence on Earth." Kara clarified for him and Barry then thought that the DEO sounded it was like ARGUS on his Earth.

"Well did Clark know about you two?" Eliza asked as Kara's eyes widened and Eliza looked shocked when she saw that Barry looked confused. "You haven't told Barry about Clark yet, have you?" Eliza asked and Kara quickly told Barry that Clark was Superman, her cousin that was raised on Earth. Barry had known about Superman but had yet to be referred to by Kara as anything but Superman, her cousin or Kal El.

As Barry and Eliza talked to eachother, Kara smiled at the fact that Barry got along with her friends and loved ones just fine, she also hoped that she could get to know his loved ones and friends as well as Caitlin and Cisco.

 **I was hoping to start the adventure part of this story but I think I want to save that for a sequel. I am going to end this here but I hope to have the sequel sometime in the next week. Can I ask for advice, what villains on Barry's earth do you think can work as a villain for a sequel to this story?**


End file.
